Ink drying equipment for web printing machines



June 16, 1953 w. c. WlEKlNG INK DRYING EQUIPMENT FOR WEB PRINTING MACHINES Filed Nov. 29, 1944 2 Sheets-Sheet l INVENTOR ATTORNEY W. C. WIEKING June 16, 1953 INK DRYING EQUIPMENT FOR WEB PRINTING MACHINES Filed Nov. 29, 1944 2 Sheets-Sheet 2 INVENTOR ATT RNEY Patented June 16, 1953 INKDRYING EQUIPMENT Eon WEB PRINTING MACHINES William (1. Wieking, WoodhavenQNQ-Yg assignor.

to R.-. Ho'e 8: (log. Inc., New poration of New York York Y.,. a cor--- Application November 29, 1944, Serial No. scares 1 can. (:01. 101-416 This invention relates to a method and means for drying freshly printed sheets or webs: and the i'nk'deposited thereon and more particularly, to the use of equipment employing high irequency electric currents for this purpose.

Heaters heretofore used have usuallybeen of the-gas fired or electric resistance type, that heated not only the ink and the web but also the surrounding air. High frequency dielectric type heaters, heretofore used, have not been entirely satisfactory for heating ink deposited on thin, fast-moving, freshl printed sheets or webs and it is therefore one object of the invention to provide a new and improved high frequency dielectric heating device which is suitable for drying the ink-on fast-moving sheets or webs.-

Another object of the invention is to provide a new and improved high frequency dielectric heating' device for use in drying thin sheets or webs and the ink printed thereon without heating the surrounding air.

Another object of the invention is to provide anewmethod and means for increasing the ability of a freshly printed sheet or web and ink printed thereon, to absorb heating energy from high frequency heating devices.

Another object of the invention is to provide a new and improved high frequency dielectricheating device in which the heating effect can be varied as the speed of the machine is varied.

Another object of the invention is to increase the heating effect produced in the ink'andthe sheet by the use of ,an atomizer for spraying the sheet with a material havinga high power factor.

Still another object of the invention is to provide a plurality of separatedielectric heating devices" that may operate at different voltages and frequencies to. dry a sheet or web and ink printed thereon.

It is also an object of the invention to provide a means whereby electrodes of a high frequency electric power source can be placed closeto a freshly printed sheet or web without causingcorona or arcingbetween the electrodes.

In accordance with one form of the invention a'fieshly printed surface in the form of along continuous sheet is passed between a plurality of paired electrodes located close to the sheet. The paired electrodes are connected together and alternate pairs are energized from a source of high frequency electric energy. I

For a more complete-understanding of; the inventiori reference-"should :be had to the accompaning drawings in which;

Figure 1 is a diagrammatic front view showin a means for drying a freshlyprinted sheet and the ink deposited thereon inaccordancewith one form of the invention-7 I r Figure 2- is a side view of'the major portion oi 2 the-apparatus shown in li-igure I, looking in the direction of the arrow 2, and including some features not shown in Figure l. v

Figure 3 is an enlargement: of a portion of Fig' ure 2 showing the electric fieldsurrounding: the electrodes when a sheet is not present;

Figure 4 is an enlargement. similar to Figure 3 showing the electric held when a freshly printed sheet is present;

Figure 5 shows a modified form of the invention in which the electrodes are positioned diagonally withrespect to the direction of sheet travel;

Figure '6' is a further modification of the invention showing ring type electrodes for heating particular portions of a printed sheet.

Figure 7'is a'v'i'e-wtaken along the broken line 1-1 of Figure 6. I

Referringto the embodiment of the invention illustrated in Figures 1 to 4,'nu-meral I'F indicates a sheet-moving from a-sourceof supply notshown) in the-direction of an arrow 12. As the sheet H passes between a pair of cooperating printing cylinders i3 and I4, one or both sides of the sheet are printed with fresh web ink- H) r in a'manner Well known inthe art. From the printing couple the freshly printed sheet I is led past one-or more spray guns [5, of any well known type, and which may be located on either orboth sides of the sheet. The sheet is then ledbetween-lower rows t5"- and l t, and then b'e-- tween the upper rows P8 and. I9 of semi-circular rod-like electrodes or terminals located in planes close to and parallel to the sheet H. shown in Figures 1 and 2, the axes oi'the rod-like electrodes ortermi-nals are. perpendicular to the directionof sheet travel, and the electrodes of opposite polarity are spaced much farther apart lengthwise: ofit'hezsheet it than are the electrodes tween the rows of electrodes; the; sheet is led through a. refrigerated cooling: box 2:] to another portion of the printing machine.

Figures 1 and: show a plurality, in this case two, of any well known type: of high frequency oscillators and 23. The oscillators are supswitch may be operated from; any convenient portion of the printing machine, as for example, from a. shaft 29. of the printing cylinder. I13. Whenthe: printing cylinder t3 and [:4 are" rotating; at printing speed,. the switch 21 will close.

to energize the: oscillators; 22. and 23, but the instant the speed of the printing machine. drops below a precletjermined;point: the switch 21 will As: best 3 open to deenergize the oscillators by disconnecting them from the line Ll.

From each of the two oscillators 22 and 23, a separate coaxial or concentric cable 32 and 33, having external conductors 34 and 36 and central conductors 3'! and 38, respectively, extends in the case of the oscillator 22 to the group of electrodes in upper rows l8 and I9, and in the case of oscillator 23 to the group of electrodes in lower rows I6 and IT. Variable inductances 39 and 4| are connected between the central and external conductors of the cables 32 and Y33 respectively, at points close to where the conductors are attached to the rows of electrodes.

Alternate electrodes of each row are joined at respectively opposite ends by connectors having a plurality of arcuate loops. Specifically a plurality of first upper electrodes 42, 43, and 44 are joined at one end by a connector 46, which is attached to the central conductor 31 of the cables 32, and a plurality of second upper electrodes 41, 48, and 48 are joined at the opposite end by a connector which is attached to the external conductor 34 of the cable 32. A plurality of third upper electrodes 52, 53 and 54 are joined by a connector 56 which is attached to the conductor 31, and a plurality of third upper electrodes 51, 58 and 59 are joined by a connector GI attached to the conductor 34. Similarly a plurality of first lower electrodes 52, 63, and 64 are joined at one end by a connector 65 which is attached to the central conductor 38 of the cable 33, and a plurality of second lower electrodes 67, 68, 69 are joined at the opposite end by a connector H which is attached to the external conductor 36 of the cable 33. A plurality of third lower electrodes 12, 13, and 14 are joined by a connector 15 which is attached to the conductor 38, and fourth lower electrodes Ti, 18, and F9 are joined by a connector 8| which is attached to the conductor 36. Thus alternate pairs of electrodes are energized at the same electrical potential. Also electrodes adjacently located on opposite sides of the sheet are energized from the same conductor and hereinafter these electrodes will be referred to as paired electrodes. For example, the paired electrodes 42 and 52 are at the same electrical potential, since they are both connected by way of connectors 46 and 56 to the conductors 31. Likewise electrodes 43 and 53 are paired electrodes. The electrodes 62, 52, 43, 53, 44, and 54 are all energized from the central conductor 31 of the cable 32, while the electrodes 41, 51, 48, 58, 49, and 59 are energized from the external conductor 34 of the cable 32. Thus, the electrodes that are all connected to the same conductor may be considered a set. Since electrodes located. on opposite sides of the sheet are energized at the same electrical potential, no electrical field will exist therebetween, and thus they can be located close to the sheet and as close to one another as desirable without the formation of corona or arcing. Also the paired electrodes located adjacent one another lengthwise of the sheet are energized at opposite polarity, for example, the paired electrodes 42-52 and 4'l51 are energized at opposite polarity, but since they are spaced at a distance lengthwise of the web, corona or arcing will not form. The drawings show only a few electrodes for each of the upper and lower groups. .However, it will be understood that a greater or lesser number of electrodes maybe employed. 1

The refrigerated cooling box 2|, may be of any suitable form, but as shown in the drawings comprises a casing with openings 82 and 83 for the freshly printed and heated sheet H to pass through. A plurality of refrigerated pipes 84, a baffle 86, and a number of deflectors 81 are located on both sides of the sheet. Circulating fans 88 are provided to force air, cooled by the pipes 84, against both sides of the printed sheet H. The fans 88 may be operated from a motor 89 through drive shafts 9| and cooperating bevel gears 92. Preferably the air will be circulated from the fan past the pipes 84 so that the coolest portion of the air contacts the sheet just before it leaves the refrigerated box.

Figures 3 and 4 show an approximate plot of the electric field which exists between adjacent paired electrodes. Figure 3 shows the field for the two sets of electrified terminals or electrodes I6 and I! at a time when a freshly printed sheet is not present therebetween. This condition, While seldom if ever met in practice, when considered in connection with the condition illustrated in Figure 4, indicates how the ink and a freshly printed sheet is dried by means of a high frequency electric field. In Figure 3 the field between the electrodes is undistorted while in Figure 4 the electric field is distorted due to the presence of the ink ID on the freshly printed web or sheet II. It will be understood that the wet ink and the sheet have higher power factors than the air, and therefore provides a better path for the heating energy passing between the electrodes. As one means for insuring that the freshly printed wet ink will have a power factor much greater than the surrounding air and the sheet II, it is preferable to use an ink containing a material having a high power factor as for example a soluble resin although other materials may be used.

It will also be understood that some portions of a freshly printed sheet receive more wet ink than other portions, and therefore the power factor of all portions of an average freshly printed sheet will not be the same. Consideration of many printed pages will show that a horizontal line drawn through a line of printed matter, traverses more printed area than does a vertical line through the same page. Therefore the power factor of a freshly printed page with wet ink as measured horizontally will generally be greater than the power factor of the same page as measured from top to bottom.

Since the electrodes shown in Figures 1 and 2 I printed lines are collinear with the direction of sheet movement.

The oscillators 22 and 23 may be of any standard design, well known in the electrical art, and i preferably will be capable of generating electrical energy having a frequency within the range used for high frequency dielectric heating. While the illustrated embodiment of the invention shows two separate oscillators, it will be understood that, under some circumstances, satisfactory results may be obtained by the use of one naster;

oscillator having a plurality of pick-up coils coupled to a single master tank circuit. Preferably the oscillator 23 for energizing the lower sets of electrodes I6 and I? will be operated at a lower voltage than the oscillator 22 for energizing the upper rows of electrodes I8 and I9. As the printed sheet is heated by the lower set of electrodes it becomes partly dried and its power factor changes. Therefore a higher voltage at a suitable frequency, may advantageously be used for heating the partly dried sheet. It will be understood that more than two oscillators and more than two sets of paired terminals may be used if desired.

A means for regulating the energy produced by oscillators 22 and 23, as the speed of the printing machine varies, is included and comprises a Selsyn or similar transmitter I I I driven by a shaft I I2 of rheostat I I3 controlled by a pilot motor I I4. It will be understood that the rheostat H3 and pilot motor I I4 are used to regulat the speed of the printing machine and thus the rate at which the web I I is printed. A Selsyn or similar receiver II5, electrically connected to the transmitter I II in a well known manner, drives a shaft H6 that by means of coupling I I 9, worm gears I I! and I I8, and shafts IZI regulate the energy produced by the oscillators 22 and 23. Increasing the speed Y of the printing machine will thus increase the energy produced by the oscillators and thus will increase the amount of heat generated in the freshly printed ink I and web II. The couplings H9 positioned between the receiver H and the worms Ill, and H8 permit the receiver M5 to control either one or both of the shafts I2I and thus to control the energy produced by either one or both of the oscillators. Toggle switches I on each of the oscillators 22 and 23 may be used to shut off the primary current, feeding from the lines LI and L2 to the oscillators. It will be understood that a slow moving sheet requires less electrical energy to dry the ink than does a fast moving one. By the means disclosed it is possible to increase or decrease the amount of heating applied to the ink I0 and the sheet II as the speed of printing is increased or decreased.

A modified form of the invention, shown in Figure 5, is similar to the hereinbefore described device except that the semicircular rod type electrodes, for example electrodes 92, 93, and 94, which are located in planes close to the sheet and are connected by a connector 95, have their axes at an angle of approximately forty-five degrees with the direction of sheet movement. This produces an electrical field which extends at an angle of forty-five (45) degrees with the direction of movement of the sheet II and is most advantageously employed for drying the ink on a.

freshly printed sheet which has printed lines running perpendicular to the direction of sheet movement. In this case the electric lines of force have components which are parallel to the printed lines. The type of heater shown in Figure 5, is also useful for drying freshly printed ink on sheets containing illustration, etc., Where no particular printed pattern predominates. In order that the greatest amount of heat may be generated in the ink I0 and the sheet II, it is desirable to increase the power factor of the ink and the sheet. To this end there has been provided a plurality of spray guns I 5 for spraying the sheet II with a solution having a high power factor as for example a quick drying volatile solution of a colorless resin, although other materials may be used.

The embodiment of the invention shown in Figures 6 and 7 comprises a plurality of concern trically placed ring type electrodes 96, 91, 93 and 99, alternately joined by connectors I '99 and III}, and energized from an internal conductor 56d and an external conductor 402 of a concentric cable I03 respectively. This device is primarily adapted for drying particularly wet portions of a printed sheet and may be of a large or small diameter as required. The electrodes 96 and 98 are joined by the connector H9 which is attached to the conductor I02, and the electrodes 97 and 99 are joined by the connector I00 which is attached to conductor I0 I, while the cable I93 may be energized from a high frequency oscillator not shown.

The term sheet as used herein includes a long sheet or web of paper such as is printed by web fed printing machines.

' It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, and it will be further understood that each and every novel feature and combination present in or possessed by the mechanism herein disclosed forms a part of the invention included in this application.

What I claim is:

In an ink drying equipment for a printing machine, a source of high frequency electrical energy having two external conductors, two sets of closely spaced pairs of electrodes mounted in parallelism and with one electrode onv each side of a path through which sheets are led from printing cylinders of the machine, the said electrodes being mounted diagonally with respect to the said path, the two electrodes of each pair being connected together and the electrode pairs of each set being electrically connected together, the pairs of electrodes alternatin in sequence so that pairs of electrodes of each set are interposed between pairs of electrodes of the other set, and a connection from one of the said conductors to one set of electrode pairs and a connection from the other conductor to the second set of electrode pairs.

WILLIAM C. WIEKING.

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Mittelmann Apr. 2, 1946 

